Oct 2017 Funding announced for Leverhulme Research Project Grant The Nature of Interatomic Forces in Metallic Systems. Investigators are Prof. Christoph Ortner and myself. Project will run from April 2018 for four years and support two postdoctoral researchers.

Research Interests

I develop multiscale materials modelling algorithms and the software that implements them. My recent work applies this parameter-free modelling to make quantitative predictions of "chemomechanical" materials failure processes where stress and chemistry are tightly coupled, e.g. near the tip of a propagating crack (left), where local bond-breaking chemistry is driven by long-range stress fields. Recents projects include:

Slow Crack Growth in Brittle Crystals. Everyday experience suggests that when brittle materials like glass or silicon wafers break they crack very fast, usually at a large fraction of the speed of sound in the material. In research published in Physical Review Letters, we presented QM-based atomistic simulations together with new experimental results from collaborators at the Technion in Israel that overturn this intuition, showing how cracks in silicon can propagate very slowly via intrinsically 3D kink mechanisms.

Molecular Dynamics with On-the-fly Machine Learning of Quantum Mechanical Forces. In an article published in Physical Review Letters, we report a new molecular dynamics scheme which combines first-principles molecular dynamics and machine-learning (ML) techniques in a single information-efficient approach. The scheme works by going “shopping” in a database of reference configurations whenever QM forces are required. If there’s something similar enough, it interpolates using Bayesian inference to predict forces. If not, a new QM calculation is carried out on the fly to extend the database (Read more).

Scattering of cracks by individual atomic-scale impurities. In an article published in Nature Communications, we showed that a single atomic defect (e.g. a boron dopant, coloured orange in movie, above right) can be enough to deflect a crack as it travels through a crystal, leading to macroscopically observable surface features (centre right).

Low speed fracture instabilities. In an earlier work published in Nature, we discovered that the (111) cleavage plane in silicon becomes unstable at speeds below about 1000 m/s. The instability arises from an atomic scale reconstruction of the crack tip which can only be accurately modelled with quantum mechanical precision.

I hold a Royal Society Research Project Grant (April 2017-Mar 2018) Bridging from Quantum Mechanical to Continuum Mechanical Models of Fracture, which provides funding for local computational resources.

The Novel Materials Discovery (NoMaD) laboratory, funded under the Horizon 2020 Centre of Excellence initiative, will enable access to the huge amount of data routinely produced by computational materials science calculations through the online NoMaD repository. I am a senior researcher within the project, which is led by the Fritz Haber Institute and involves a consortium of 11 organisations throughout Europe. This project supports my postdoc Dr Berk Onat.

Multiscale Atomistic Simulation of the Mechanical Behaviour of Nickel-based Superalloys. Project allocated 20 million core hours at the Cineca and Jülich supercomputer centres. Other project members are Federico Bianchini, Alessio Comisso and Alessandro De Vita (all at King's).